The primary reason why the RuO2(1 1 0) surface is much more active in the oxidation of CO than the corresponding metal Ru(0 0 0 1) surface is correlated with the weaker oxygen bonding on RuO2(0 1 0) compared to chemisorbed oxygen on Ru(0 0 0 1). The RuO2(1 1 0) surface stabilizes at least two potentially active oxygen species, i.e., bridging O and on-top O atoms. Together with various adsorption sites for CO during the reaction, the CO oxidation reaction over RuO2 (0 1 0) becomes quite complex. Using the techniques of temperature programmed reaction and desorption in combination with state-of-the-art density functional theory calculation we studied the CO oxidation reaction over RuO2 (0 1 0) in the temperature range of 300-400 K. We show that the CO oxidation on RuO2(0 1 0) surface is not dominated by the recombination of CO with on-top O, although the binding energy of the on-top O is 1.4 eV lower than that of the bridging O atom.